The invention relates to a process for the production of a free flowing, filled elastomer powder by combining, under stirring, an aqueous elastomer latex which contains auxiliary agents with an aqueous filler suspension, separating the aqueous phase and finally drying the elastomer powder under constant agitation. The invention also relates to pourable, filled elastomer powders produced according to this process.
The manufacture of pourable, filled elastomer powders is basically conventional. Thus, German Pat. No. 2,822,148 discloses, inter alia, the production of pourable, filled elastomer powders. An essential feature in the known mode of operation resides in having to set a very narrow, acidic pH range, the precipitation of the elastomer having to be executed perforce in the presence of water glass and aluminum salts. On account of this fact, the finished elastomer powder contains in every case silicon compounds and aluminum compounds as troublesome filler components. It has furthermore been found under practical conditions that the resultant elastomer powders, for example at low-filler grades, exhibit low mechanical stability since they are too soft, or, for example in case of high filler contents, tend very strongly to produce undesirable, i.e. dangerous, dust emission.
Polyamines are known in industry as flocculating agents. They serve the purpose of precipitating, quickly and completely, very fine and difficult to separate particles (slurries). The thus-precipitated particles are obtained as flocs of irregular shape and size.
Low-molecular-weight polyamines have been disclosed for the plastics industry (German Pat. No. 1,195,941). According to the cited reference, these low-molecular-weight polyamines are utilized, inter alia, for the production of elastomer/silicic acid mixtures. As a special feature, the disclosure mentions that the latex utilized must have been prepared using specific emulsifiers. According to this reference, it is not possible to make use of the entire spectrum of usable emulsifiers and/or fillers. The disclosure does not include the production of free flowing elastomer powder.